Some friends used to paint complementary colors as borders of some images to make them shine!

On the other hand, when doing this effect inside a color symphony (or color salad) the results are difficult to predict...

Perhaps, doing a 'weird' color average of an image it could be possible to know the resulting ghost-layer's color? It is not a color competition, but a color symphony. There is taste involved. Or human perception ( or limitation of perception ). Just adding and substracting colors through all the image, I guess (not sure)...